gssd_proc: use pollsize, not FD_ALLOC_BLOCK, in get_poll_index()

get_poll_index wants to walk the entire "pollarray", but uses
the constant FD_ALLOC_BLOCK, rather than the variable
pollsize (which has the same value).  If we want to make the
size of the array variable, it is best not to use the constant.

As pollsize is 'unsigned long', 'i' should be too.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Steve Dickson <steved@redhat.com>